Patients suffering from neurodegenerative diseases or brain damage such as is caused by stroke or head injury often are afflicted with emotional problems associated with the disease or injury. The terms emotional lability and pseudobulbar affect are used by psychiatrists and neurologists to refer to a set of symptoms that are often observed in patients who have suffered a brain insult such as a head injury, stroke, brain tumor, or encephalitis, or who are suffering from a progressive neurodegenerative disease such as Amyotrophic Lateral Sclerosis (ALS, also called motor neuron disease or Lou Gehrig's disease), Parkinson's disease, Alzheimer's disease, or multiple sclerosis. In the great majority of such cases, emotional lability occurs in patients who have bilateral damage (damage which affects both hemispheres of the brain) involving subcortical forebrain structures.
Emotional lability, which is distinct from clinical forms of reactive or endogenous depression, is characterized by intermittent spasmodic outbursts of emotion (usually manifested as intense or even explosive crying or laughing) at inappropriate times or in the absence of any particular provocation. Emotional lability or pseudobulbar affect is also referred to by the terms emotionalism, emotional incontinence, emotional discontrol, excessive emotionalism, and pathological laughing and crying. The feelings that accompany emotional lability are often described in words such as “disconnectedness,” since patients are fully aware that an outburst is not appropriate in a particular situation, but they do not have control over their emotional displays.
Emotional lability or pseudobulbar affect becomes a clinical problem when the inability to control emotional outbursts interferes in a substantial way with the ability to engage in family, personal, or business affairs. For example, a businessman suffering from early-stage ALS or Parkinson's disease might become unable to sit through business meetings, or a patient might become unable to go out in public, such as to a restaurant or movie, due to transient but intense inability to keep from crying or laughing at inappropriate times in front of other people. These symptoms can occur even though the patient still has more than enough energy and stamina to do the physical tasks necessary to interact with other people. Such outbursts, along with the feelings of annoyance, inadequacy, and confusion that they usually generate and the visible effects they have on other people, can severely aggravate the other symptoms of the disease; they lead to feelings of ostracism, alienation, and isolation, and they can render it very difficult for friends and family members to provide tolerant and caring emotional support for the patient.